The present invention relates to an electrical generator for a sailboat. More particularly this invention concerns such a generator which employs the motion of the sailboat through the water in order to generate electricity.
A sailboat is frequently provided with a substantial quantity of electronic and electrical equipment, such as radios, lights, refrigeration equipment, and miscellaneous marine instrumentation devices. This equipment is all powered normally by the on-board ship's battery.
A constant problem for the operator of such sailboat is keeping this battery charged so that all the above-mentioned equipment can be used. Normally this is simply done by running the auxiliary engine periodically. A generator on this engine is connected to the battery and charges it. Such periodic running of the auxiliary engine is not only a bother and tends to wear out the engine, but also destroys the tranquility of the sail and often consumes a disproportionately large amount of fuel. Since the battery is normally rather large, in the 100 or 200 ampere-hour size, the charging operation takes a relatively long time also. Furthermore, it is noted that in some locations running of the engine is not only discouraged but virtually illegal except in emergency circumstances.
It has been suggested to employ a windmill-type device to generate electricity on a sailboat. Obviously, such an arrangement will not work at all in a dead run, and at best can only be counted on the produce a very minimal amount of electricity. The use of solar cells has similarly proven itself impractical.
In yet another solution the propeller of the auxiliary engine on the sailboat can be uncoupled from this engine but left coupled with the on-board generator. Thus as the ship is moving through the water under sail power the water moving relative to the ship will rotate this propeller and the generator and allow the battery to be trickle charged. This system has also been proven to be extremely inefficient, as the propeller, which is designed to drive the boat through the water using several horsepowers of torque is very inefficient when used in reverse fashion to drive the generator. Indeed often the friction in the stuffing box alone is so great as to use up most of the work created by rotation of the propeller by means of the water through which the boat is passing.